Environmental considerations have led to the development of a container unit providing improved containment of hazardous liquids. In an indoor environment, where small capacity storage is needed, adequate containment is essential for personal safety. This invention provides secondary containment of the primary tank and thus prevents release of the hazardous liquid to the environment.
In accordance with the present invention, the storage container unit comprises an inner tank for containing a hazardous liquid, disposed within an outer tank. The side wall of the inner tank is spaced inwardly from the side wall of the outer tank to provide an annular air chamber. The top wall of the inner tank has a radially outwardly extending annular lip which overlaps an annular flange on the upper edge of the side wall of the outer tank to close the air chamber. The outer tank and air chamber provide a secondary dike against the escape of hazardous liquid, and also prevents accidental contamination of the annual space.
Preferably, the base of the outer tank is shaped to provide channels in the underside to receive the fork of a lift truck, and ribs on the upper side for supporting the base of the inner tank above the base of the outer tank to extend the air chamber beneath the inner tank.
The top wall of the inner tank has a fill opening, and a removable cap for the fill opening preferably has a vent plug for blowing out in the event of excess pressure in the inner tank. The storage container unit may also include a liquid level indicator to indicate the level of liquid in the inner tank.
The inner tank also desirably has a pump and a suction line to a sump in the bottom of the inner tank for a more complete removable of the liquid in the tank.
It is an object of this invention to provide a storage container unit having the above features.
Another object is to provide a storage container unit which is composed of a relatively few simple parts, is rugged and durable in use, and is easy to manufacture and assemble.
Other objects, features and advantages of the invention will become more apparent as the follow description proceeds, especially when taken with the accompanying drawings.